Ultrasonic air and blood foam detector

Abstract

An ultrasonic air and blood foam detector for use in medical procedures involving extracorporeal handling of blood. A sensor assembly is adapted for positioning about a blood drip chamber and contains ultrasonic transducer means. The blood tube downstream from the drip chamber is preferably placed through the controllable clamp. Electronic circuitry provides excitation to the ultrasonic transducer means and signals transmitted through the chamber are received, amplified and processed by a level detector which provides an output signal for actuating the clamp when a predetermined low signal level occurs, indicating excessive air or foam in the drip chamber. In the preferred embodiment, a clip-on sensor assembly having epoxy lenses is provided.

We claim: 
     
       1. An ultrasonic air and blood foam detector for use with a blood tube system including a drip chamber, comprising: a. ultrasonic sensing means adapted for positioning adjacent a blood drip chamber and having ultrasonic transducer means mounted within said sensing means and positioned for contact with said drip chamber;   b. energization means connected to said transducer means for causing ultrasonic energy to be transmitted through said blood drip chamber;   c. electronic signal detection means operatively connected to said transducer means for receiving signals transmitted through said blood drip chamber and operable in response to the signal level of the received ultrasonic signal to produce an output signal indicative of the presence of air or blood foam in said chamber; and   d. said ultrasonic sensing means including a polymeric material lens on the surface of said ultrasonic transducer means for contact with the side of said drip chamber, said lens having a convex surface.   
     
     
       2. A detector according to claim 1 wherein said energization means is adapted for applying pulsed energization to said transducer means. 
     
     
       3. A detector according to claim 1 wherein said energization means is adapted for applying bursts of gated sinusoid wave energization to said transducer means. 
     
     
       4. A detector according to claim 1 wherein said energization means is adapted for providing continuous wave energization to said transducer means. 
     
     
       5. A detector according to claim 1 wherein said ultrasonic sensing means includes a single ultrasonic transducer and further including switching means for alternately connecting said transducer to said energization means and to said electronic signal level detection means, whereby ultrasonic energy may be received after transmission through the blood drip chamber and reflection back to the transducer. 
     
     
       6. A detector according to claim 1 further including tube clamp means for positioning adjacent a blood tube associated with said drip chamber, and connected to said signal level detection means, said tube clamp means operable for selectively clamping the tube to prevent flow therethrough in response to said output signal when said output signal indicates the presence of air or blood foam in the drip chamber. 
     
     
       7. An ultrasonic air and blood foam detector for use with a blood tube system including a drip chamber comprising: a. a sensor housing adapted for positioning adjacent a blood drip chamber;   b. a pair of ultrasonic transducers mounted in said housing for positioning against opposite sides of the drip chamber;   c. tube clamp means comprising means defining a tube receiving channel, a pair of tube clamp members positioned on opposite sides of said channel, a movable actuator arm mounting one of said tube clamp members, spring bias means connected to said actuator arm for urging said tube clamp towards a closed position, and means for selectively holding said actuator arm in an open position;   d. energization means connected to one of said transducers for causing ultrasonic acoustic energy to be transmitted therefrom through the drip chamber;   e. amplifier means connected to the other of said transducers for amplifying signals transmitted through the drip chamber and received by said transducer;   f. signal level detection means connected to said amplifier means, for detecting the level of the received signals;   g. switching means connected to said signal level detection means and to said means for selectively holding said actuator arm, said switching means operable to cause release of said actuator arm to clamp said tube when a predetermined signal level is detected indicating presence of air or blood foam in the drip chamber; and acoustic lens members attached to the pair of ultrasonic transducers for contact with the sides of the drip chamber, said acoustic lens members comprising layers of polymeric material coated on said transducers.   
     
     
       8. A detector according to claim 7 wherein said acoustic lens members have a convex configuration. 
     
     
       9. A detector according to claim 8 wherein said energization means is adapted for providing continuous wave energization to said one transducer. 
     
     
       10. An ultrasonic air and blood foam detector for use with a blood tube system including a drip chamber, comprising: a. an ultrasonic sensor assembly including a pair of sensor body members, means slideably interconnecting said members for permitting relative motion of said members towards and away from each other, said sensor body members configured to form a drip chamber receiving area therebetween, and an ultrasonic transducer crystal mounted in at least one of said body members and positioned for contacting the side of a blood drip chamber when positioned in said receiving area;   b. energization means connected to said sensor assembly for causing ultrasonic energy to be transmitted through said blood drip chamber; and   c. electronic signal level detection means operatively connected to said sensor assembly for receiving signals transmitted through said blood drip chamber and operable in response to the signal level of the received ultrasonic signals to produce an output signal indicative of the presence of air or blood foam in said chamber.   
     
     
       11. A detector according to claim 10 further including tube clamp means for positioning adjacent a blood tube associated with the blood drip chamber, and connected to said electronic signal level detection means, said tube clamp means operable for selectively clamping the tube to prevent flow therethrough in response to said output signal. 
     
     
       12. A detector according to claim 10 wherein said ultrasonic sensor assembly further includes a polymeric material layer on said crystal shaped to form a lens for ultrasonic energy and positioned for contacting the side of a blood drip chamber when positioned in said receiving area. 
     
     
       13. A detector according to claim 10 wherein said ultrasonic sensor assembly includes a pair of ultrasonic transducer crystals, one mounted in each of said sensor body members, and wherein said energization means is connected to one of said transducer crystals, and said electronic signal level detection means is connected to the other of said transducer crystals. 
     
     
       14. A detector according to claim 10 wherein said energization means is adapted for applying pulsed energization to said ultrasonic sensor assembly. 
     
     
       15. A detector according to claim 10 wherein said energization means is adapted for providing bursts of gated sinusoidal wave energization to said ultrasonic sensor assembly. 
     
     
       16. A detector according to claim 10 wherein said energization means is adapted for providing continuous wave energization to said ultrasonic sensor assembly. 
     
     
       17. A detector according to claim 10 further including switching means for alternately connecting said ultrasonic transducer crystal to said energization means and to said electronic signal level detection means, whereby ultrasonic energy may be received after transmission through the blood drip chamber and reflection back to the transducer crystal.